Contents
Stereo recording is a technique used to capture the full breadth of sound from a single instrument. It is achieved by using two microphones simultaneously and is a popular choice among audio engineers for its ability to create a sense of width and depth in recordings.
In this article, we will discuss the five most popular methods of stereo recording: A/B, X/Y, ORTF, Blumlein Pair, and Mid/Side.
Whether you’re a beginner or experienced, this article will help you gain a better understanding of stereo recording and its various methods.
Key Takeaways
- Stereo recording involves using two microphones to capture the sound of one instrument.
- Different techniques such as A/B Stereo Recording, X/Y Stereo Recording, ORTF Stereo Recording, Blumlein Pair, and Mid/Side Stereo Recording can be used for stereo recording.
- A/B Stereo Recording utilizes two omnidirectional mics and captures a sense of width through differences in timing and frequency balance.
- X/Y Stereo Recording uses two directional mics angled between 90-135 degrees and creates a stereo effect through differences in frequency balance.
A/B Stereo Recording
Taking stereo recording to the next level, A/B stereo recording involves positioning two omnidirectional mics to capture a wider soundscape.
The main benefit of using omnidirectional mics for A/B stereo recording is that they pick up sound from all directions, providing a broad stereo image.
The drawback is that they also pick up a lot of ambient room sound.
To create a wider stereo image, adjust the distance of the mics from the instrument and from each other.
By positioning the mics further apart and closer to the instrument, the stereo image will be widened.
Mix the mono signals from each microphone to the left and right channels of a stereo track.
This technique creates the stereo effect from the staggered time of arrival at each microphone and the different frequency balance.
X/Y Stereo Recording
The next method of stereo recording is X/Y stereo recording, which combines the directional mics of A/B stereo recording with the physical spacing of the mics.
Two directional mics, usually small diaphragm condensers, are angled between 90-135 degrees so that their capsules coincide at a single point. This technique has less of a stereo effect compared to A/B recording due to no differences in timing, but the stereo effect is created from the differences in frequency balance.
When used correctly, X/Y stereo recording has several advantages such as capturing a wide range of sonic information and allowing for greater control of the stereo image.
To achieve optimal X/Y microphone positioning, the mics should be spaced two feet apart at a distance of a foot from the instrument. Experimenting with the distance of the mics from the instrument can yield interesting results.
ORTF Stereo Recording
ORTF stereo recording combines the physical spacing of A/B recording with the directional mics of X/Y recording. This technique yields a wider stereo image and captures less ambient room sound than other techniques.
Two directional mics, usually small diaphragm condensers, are placed outward at an angle of 110 degrees, with the capsules spaced 17cm apart. The mix of the mono signals from each microphone is then assigned to the left and right channels of a stereo track.
To achieve optimal results with ORTF stereo recording, experiment with adjusting the distance of the mics from the instrument and from each other, and consider the acoustics of the recording environment.
With its advantageous combination of physical spacing and directional mics, ORTF stereo recording provides a wide and detailed stereo image with less room ambience.
Blumlein Pair
Blumlein Pair is a stereo recording technique that requires two figure 8 (bi-directional) mics. It has the same positioning as X/Y technique and the same signal mixing as X/Y, but with the added benefit of capturing more room sound. This yields a wider stereo image and more ambience to the recording.
Compared to other stereo recording methods, the advantages and disadvantages of Blumlein pair are that it offers a larger stereo image and more room ambience, but with less directional information. Although the stereo image created by Blumlein pair can sound pleasing, it may not be suitable for all applications.
Mid/Side Stereo Recording
Utilizing two microphones, Mid/Side Stereo Recording is an effective way to create a wide stereo image with mono compatibility.
It employs one small diaphragm condenser mic (cardioid or omnidirectional) and one large diaphragm condenser mic (figure 8).
The figure 8 mic is placed sideways at a 90-degree angle from the instrument and the other mic is positioned on top or below the figure 8 mic, pointed directly toward the instrument.
The signals are mixed by duplicating the side channel, reversing the polarity of the duplicated channel, combining the two side channels onto one stereo track, and mixing in the mid channel for width adjustment.
This offers the advantages of A/B, X/Y, and Blumlein Pair techniques without their downsides, providing stereo width, mono compatibility, and the option to increase room ambiance.
Conclusion
Stereo recording is a powerful tool for capturing the full sound of a single instrument. By using two microphones simultaneously, the differences between the left and right audio channels are captured, creating a sense of width and depth.
The five popular methods of stereo recording are A/B, X/Y, ORTF, Blumlein Pair, and Mid/Side. Each method has its own unique benefits and drawbacks, and understanding them can help audio engineers create recordings that capture the fullest possible sound of an instrument.
I’m thrilled to be able to share my passion for music with others through this audio blog, and I can’t wait to connect with fellow music lovers from all around the world. Let’s rock on!